adds codes for curacao and kosovo
Merge pull request #25 from Shopify/feature/add_kosovo_and_curacao

adds codes for curacao and kosovo
version bump for new countries
Merge pull request #26 from Shopify/version/minor_bump_for_new_countries

version bump for new countries
Wrap Zlib::BufError in ActiveMerchant::InvalidResponseError
Merge pull request #27 from Shopify/invalid-response-error

Wrap Zlib::BufError in ActiveMerchant::InvalidResponseError
Make ActiveSupport version configurable.  Fix issues blocking spec runs on ActiveSupport 2.3.x.  Add .travis.yml file to run tests